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Boiler breakdowns: repair or replace?

Common faults, what Ross checks, and when a new boiler makes more sense.

5 min readBy Ross, Gas Safe engineerUpdated October 2026
Boiler opened for fault diagnosis by HOLMHEAT

When the heating or hot water stops, you speak to Ross, the Gas Safe registered engineer who will come out, find the fault and fix it. Gas, electric and oil boilers, all the main makes.

24 hrPhone and WhatsApp
£5mPublic liability cover
963857Gas Safe registered

What happens when you get in touch

  1. 01

    WhatsApp Ross

    Tell Ross what has stopped working, with a photo of the boiler and any fault code. Emergency? Call.

  2. 02

    Same-day response

    Ross replies the same day with the call-out fee and the earliest slot, often that day.

  3. 03

    Fault found

    Instruments, not guesswork: pressure, flue gas analysis, and flow and return temperatures.

  4. 04

    Fixed, often first visit

    Common parts are carried on the van. If one needs ordering, you get the cost first.

Before you call, check

  • Is the boiler showing a fault code? Note it, or send Ross a photo
  • Is the pressure at 0, or does it keep losing pressure?
  • Are your other gas appliances, like the hob, working (if you have any)?
  • Is the boiler display on? If it is blank, check the switch beside it
  • Is the thermostat or timer on and asking for heat?

Send what you find on WhatsApp. It helps Ross know what to bring.

Smell gas?

Open doors and windows, turn off the gas at the meter (not if it's in a cellar or basement), don't use electrical switches or naked flames, and call the National Gas Emergency Service on 0800 111 999.

Common faults Ross repairs

No heating or hot water

Ignition, gas valve, fan and flue faults traced and repaired.

Losing pressure

Leaks, expansion vessels and pressure-relief valves found and fixed.

Lockouts that keep coming back

The cause fixed, not just the boiler reset.

Noises and kettling

Sludge, scale, pumps and air locks identified and sorted.

Controls and wiring

Thermostats, valves and wiring centres diagnosed properly.

Leaks and drips

Pipework, seals, heat exchangers and condensate traced to source.

Boiler opened for fault diagnosis
Combustion check during a repair visit

Repair or replace?

Most breakdowns are worth repairing. Ross will tell you honestly when one isn't. That's when a boiler is beyond economical repair: the repair would cost a large share of a new boiler, often a major part such as the heat exchanger on an older boiler, or the parts are no longer made.

Beyond economical repair?A new boiler comes with up to 10 years' cover.

Replace it with an eligible Vaillant or Glow-worm boiler, fitted with the manufacturer's filter, and you get up to 10 years' parts and labour guarantee. If a covered fault happens in that time, the manufacturer repairs it under the guarantee, as long as the boiler is serviced every year.

You get both options priced, the repair and a new boiler, so you can choose.

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